Researchers have a made a major step forward in the development of quantum computers that can run at speeds far faster than current systems.

A Spanish team claims to have created a pair of particles with 103 dimensions.

The experiment smashes the previous record of 11 dimensions, and mean quantum computers are one step closer to becoming commonplace.

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A current quatum computer chip: Unlike 'bits' found in normal computers that can only be on or off at any one time, qubits can also be in a 'mixed state' between these points. This means quantum computers such as the D-Wave range can peform single tasks much faster than normal computers, and perform multiple tasks at once, much more efficiently. The latest breakthrough could make them even more powerful.

WHAT IS QUANTUM ENTANGLEMENT

Quantum entanglement is a physical phenomenon that occurs when pairs or groups of particles are generated or interact in ways such that the quantum state of each particle cannot be described independently – instead, a quantum state may be given for the system as a whole.

Superpositions are produced, such as the possibility of being in two places at once, which defies intuition.

In addition, when two particles are entangled a connection is generated: measuring the state of one (whether they are in one place or another, or spinning one way or another, for example) affects the state of the other particle instantly, no matter how far away from each other they are.

The discovery could represent a great advance toward the construction of quantum computers with much higher processing speeds than current ones, and toward a better encryption of information, the researchers say.

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The states in which elementary particles, such as photons, can be found have properties which are beyond common sense.

The phenomenon means that superpositions are produced, such as the possibility of being in two places at once, which defies intuition.

This allows quantum computers, for instance, to process more than one thing at a time more effectively - and makes them much quicker when processing several tasks at the same time.

In addition, when two particles are entangled a connection is generated: measuring the state of one (whether they are in one place or another, or spinning one way or another, for example) affects the state of the other particle instantly, no matter how far away from each other they are.

Scientists have spent years combining both properties to construct networks of entangled particles in a state of superposition.

This in turn allows constructing quantum computers capable of operating at unimaginable speeds, encrypting information with total security and conducting experiments in quantum mechanics which would be impossible to carry out otherwise.

An example of a two-dimensional subspace is shown. The intensities and phases for two different modes in the z basis are demonstrated, and their superposition leads to a mode in the x basis. The y basis can be constructed similarly.

Until now, in order to increase the 'computing' capacity of these particle systems, scientists have mainly turned to increasing the number of entangled particles, each of them in a two-dimensional state of superposition: a qubit (the quantum equivalent to an information bit, but with values which can be 1, 0 or an overlap of both values).

Using this method, scientists managed to entangle up to 14 particles, an authentic multitude given its experimental difficulty.

The research team was directed by Anton Zeilinger and Mario Krenn from the Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences.

It included the participation of Marcus Huber, researcher from the Group of Quantum Information and Quantum Phenomena from the UAB Department of Physics, as well as visiting researcher at the Institute of Photonic Sciences (ICFO).

The team has advanced one more step towards improving entangled quantum systems.

In an article published this week in the journal PNAS, scientists described how they managed to achieve a quantum entanglement with a minimum of 103 dimensions with only two particles.

WHAT IS QUANTUM COMPUTING?

Modern day computers run on a model designed by Alan Turing in the 1930s.

They are digital and use bits to transfer information and perform tasks.

They use binary code and can only ever been in an active, or an inactive state - running at one or zero.

This means that a single bit is either on or off at any one time.

The D-Wave quantum computer

Qubits work differently and can be on, off, or in a mixed state in between.

As a result, qubits are able to be in
multiple places at the same time.

Whereas the original Turing computer can only make one calculation at a time, quantum computers are capable of
performing single tasks faster, and performing multiple tasks more
effectively.

Tasks that would take normal computers years to complete can be processed in seconds using quantum computers like the D-Wave.

'We have two Schrödinger cats which could be alive, dead, or in 101 other states simultaneously', Huber jokes, 'plus, they are entangled in such a way that what happens to one immediately affects the other'.

The results implies a record in quantum entanglements of multiple dimensions with two particles, established until now at 11 dimensions.

Instead of entangling many particles with a qubit of information each, scientists generated one single pair of entangled photons in which each could be in more than one hundred states, or in any of the superpositions of theses states; something much easier than entangling many particles.

These highly complex states correspond to different modes in which photons may find themselves in, with a distribution of their characteristic phase, angular momentum and intensity for each mode.

'In cryptography, for example, our method would allow us to maintain the security of the information in realistic situations, with noise and interference.

'In addition, the discovery could facilitate the experimental development of quantum computers, since this would be an easier way of obtaining high dimensions of entanglement with few particles', explained researcher Marcus Huber.

Now that the results demonstrate that obtaining high dimension entanglements is accessible, scientists conclude in the paper that the next step will be to search how they can experimentally control these hundreds of spatial modes of the photons in order to conduct quantum computer operations.